You could test watch SpaceMarines new series. He is playing it ATM.
Generally the Quasar version is VB6 on speed steroids. Same game but super fast - so ideal for multi-faction or long-last games. Really neat.
The management of fleets in C# is a great improvement from VB6/Quasar; so you will miss that.
Some C# stuff Kyle has also implemented in Quasar like the Prototypes. He also copied the "No Hull" Option, but you still have to build these in a shipyard, not in a factory like in C#.
As already mentioned in C# you have to do troop management on your own as you do with ship classes. Great but time consuming feature - especially replenishing after a lossy fight. In Quasar you only have to research the already given default troop types and manage them.
VB6 still had PDCs - a nice feature which I didn't miss in C# - but I never used it that much back then. It was nice to simulate troop placement on the planet with them though.
Quasar has a functioning civilian transfer system; back in VB6 that was always a bit buggy. So nice to see that it works because it is very useful. I recently in a Quasar game blew it somehow. But if it is a bug we'll find it